Antenna System with Antenna Swapping and Antenna Tuning

ABSTRACT

Electronic devices may be provided that contain wireless communications circuitry. The wireless communications circuitry may include radio-frequency transceiver circuitry and first and second antennas. An electronic device may include a housing. The first antenna may be located at an upper end of the housing and the second antenna may be located at a lower end of the housing. A peripheral conductive member may run around the edges of the housing and may be used in forming the first and second antennas. The radio-frequency transceiver circuitry may have a transmit-receive port and a receive port. Switching circuitry may connect the first antenna to the transmit-receive port and the second antenna to the receiver port or may connect the first antenna to the receive port and the second antenna to the transmit-receive port.

This application is a continuation of U.S. patent application Ser. No.14/608,048, filed Jan. 28, 2015, which is a continuation of U.S. patentapplication Ser. No. 12/941,011, filed Nov. 5, 2010, now U.S. Pat. No.8,947,302, which are hereby incorporated by reference herein in theirentireties. This application claims the benefit of and claims priorityto U.S. patent application Ser. No. 14/608,048, filed Jan. 28, 2015 andU.S. patent application Ser. No. 12/941,011, filed Nov. 5, 2010.

BACKGROUND

This relates generally to wireless communications circuitry, and moreparticularly, to electronic devices that have wireless communicationscircuitry.

Electronic devices such as portable computers and cellular telephonesare often provided with wireless communications capabilities. Forexample, electronic devices may use long-range wireless communicationscircuitry such as cellular telephone circuitry to communicate usingcellular telephone bands at 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, and2100 MHz. Electronic devices may use short-range wireless communicationslinks to handle communications with nearby equipment. For example,electronic devices may communicate using the WiFi® (IEEE 802.11) bandsat 2.4 GHz and 5 GHz and the Bluetooth® band at 2.4 GHz.

To satisfy consumer demand for small form factor wireless devices,manufacturers are continually striving to implement wirelesscommunications circuitry such as antenna components using compactstructures. At the same time, it may be desirable to include conductivestructures in an electronic device such as metal device housingcomponents. Because conductive components can affect radio-frequencyperformance, care must be taken when incorporating antennas into anelectronic device that includes conductive structures. Moreover, caremust be taken to ensure that the antennas and wireless circuitry in adevice are able to operate satisfactorily even in areas of weakradio-frequency signal strength.

It would therefore be desirable to be able to provide improved wirelesscommunications circuitry for wireless electronic devices.

SUMMARY

Electronic devices may be provided that contain wireless communicationscircuitry. The wireless communications circuitry may includeradio-frequency transceiver circuitry and antenna structures. Anelectronic device may include a display mounted within a housing. Aperipheral conductive member may run around the edges of the display andhousing. The antenna structures may include first and second antennas.The first antenna may be located at an upper end of the housing and thesecond antenna may be located at a lower end of the housing.

The peripheral conductive member may be divided into individual segmentsby forming gaps in the peripheral conductive member at various pointsalong its length. The gaps may be filled with a dielectric. The segmentsmay be used in conjunction with an antenna ground plane to form thefirst and second antennas. For example, the first segment may be used informing a two-branch inverted-F cellular telephone antenna in the upperend of the housing and the second segment may be used in forming a loopantenna in the lower end of the housing.

The loop antenna may be configured to cover five cellular telephonebands. The inverted-F antenna may be configured to cover fewer than fivecellular telephone communications bands. A tunable matching circuit maybe coupled to the inverted-F antenna and may be used to tune theinverted-F antenna to cover desired communications bands.

The electronic device may have radio-frequency transceiver circuitrythat has a transmit-receive port and a receive port. Switching circuitrymay connect the first antenna to the transmit-receive port and thesecond antenna to the receiver port or may connect the first antenna tothe receive port and the second antenna to the transmit-receive port.Processing circuitry in the device may control the switching circuitry,the tunable matching circuit, and transmitter and receiver circuitrywithin the transceiver to ensure optimum operation in a variety ofoperating environments.

Further features of the invention, its nature and various advantageswill be more apparent from the accompanying drawings and the followingdetailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an illustrative electronic device withwireless communications circuitry in accordance with an embodiment ofthe present invention.

FIG. 2 is a schematic diagram of an illustrative electronic device withwireless communications circuitry in accordance with an embodiment ofthe present invention.

FIG. 3 is a cross-sectional end view of an illustrative electronicdevice with wireless communications circuitry in accordance with anembodiment of the present invention.

FIG. 4 is a diagram of illustrative wireless circuitry includingmultiple antennas in accordance with an embodiment of the presentinvention.

FIG. 5 is a circuit diagram of an illustrative tunable matching circuitof the type that may be used in connection with the wireless circuitryof FIG. 4 in accordance with an embodiment of the present invention.

FIG. 6 is a diagram of an electronic device of the type shown in FIG. 1showing how antennas may be formed within the device in accordance withan embodiment of the present invention.

FIG. 7 is a chart showing how antennas of the type shown in FIG. 6 maybe used in covering communications bands of interest by tuning amatching filter of the type shown in FIG. 5 and adjusting switchingcircuitry in accordance with an embodiment of the present invention.

FIG. 8 is a flow chart showing illustrative steps involved in operatingan electronic device of the type shown in FIG. 1 that includes wirelesscircuitry of the type shown in FIG. 4 in accordance with an embodimentof the present invention.

DETAILED DESCRIPTION

Electronic devices may be provided with wireless communicationscircuitry. The wireless communications circuitry may be used to supportwireless communications in multiple wireless communications bands. Thewireless communications circuitry may include one or more antennas.

The antennas can include loop antennas, inverted-F antennas, stripantennas, planar inverted-F antennas, slot antennas, hybrid antennasthat include antenna structures of more than one type, or other suitableantennas. Conductive structures for the antennas may, if desired, beformed from conductive electronic device structures. The conductiveelectronic device structures may include conductive housing structures.The housing structures may include a peripheral conductive member thatruns around the periphery of an electronic device. The peripheralconductive member may serve as a bezel for a planar structure such as adisplay, may serve as sidewall structures for a device housing, or mayform other housing structures. Gaps in the peripheral conductive membermay be associated with the antennas.

An illustrative electronic device of the type that may be provided withone or more antennas is shown in FIG. 1. Electronic device 10 may be aportable electronic device or other suitable electronic device. Forexample, electronic device 10 may be a laptop computer, a tabletcomputer, a somewhat smaller device such as a wrist-watch device,pendant device, headphone device, earpiece device, or other wearable orminiature device, a cellular telephone, a media player, etc.

Device 10 may include a housing such as housing 12. Housing 12, whichmay sometimes be referred to as a case, may be formed of plastic, glass,ceramics, fiber composites, metal (e.g., stainless steel, aluminum,etc.), other suitable materials, or a combination of these materials. Insome situations, parts of housing 12 may be formed from dielectric orother low-conductivity material. In other situations, housing 12 or atleast some of the structures that make up housing 12 may be formed frommetal elements.

Device 10 may, if desired, have a display such as display 14. Display 14may, for example, be a touch screen that incorporates capacitive touchelectrodes. Display 14 may include image pixels formed formlight-emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells,electronic ink elements, liquid crystal display (LCD) components, orother suitable image pixel structures. A cover glass layer may cover thesurface of display 14. Buttons such as button 19 may pass throughopenings in the cover glass.

Housing 12 may include structures such as peripheral member 16. Member16 may run around the rectangular periphery of device 10 and display 14.Member 16 or part of member 16 may serve as a bezel for display 14(e.g., a cosmetic trim that surrounds all four sides of display 14and/or helps hold display 14 to device 10). Member 16 may also, ifdesired, form sidewall structures for device 10.

Member 16 may be formed of a conductive material and may thereforesometimes be referred to as a peripheral conductive member or conductivehousing structures. Member 16 may be formed from a metal such asstainless steel, aluminum, or other suitable materials. One, two, ormore than two separate structures may be used in forming member 16. In atypical configuration, member 16 may have a thickness (dimension TT) ofabout 0.1 mm to 3 mm (as an example). The sidewall portions of member 16may, as an example, be substantially vertical (parallel to vertical axisV). Parallel to axis V, member 16 may have a dimension TZ of about 1 mmto 2 cm (as an example). The aspect ratio R of member 16 (i.e., theratio R of TZ to TT) is typically more than 1 (i.e., R may be greaterthan or equal to 1, greater than or equal to 2, greater than or equal to4, greater than or equal to 10, etc.).

It is not necessary for member 16 to have a uniform cross-section. Forexample, the top portion of member 16 may, if desired, have an inwardlyprotruding lip that helps hold display 14 in place. If desired, thebottom portion of member 16 may also have an enlarged lip (e.g., in theplane of the rear surface of device 10). In the example of FIG. 1,member 16 has substantially straight vertical sidewalls. This is merelyillustrative. The sidewalls of member 16 may be curved or may have anyother suitable shape. In some configurations (e.g., when member 16serves as a bezel for display 14), member 16 may run around the lip ofhousing 12 (i.e., member 16 may cover only the edge of housing 12 thatsurrounds display 14 and not the rear edge of the sidewalls of housing12).

Display 14 may include conductive structures such as an array ofcapacitive electrodes, conductive lines for addressing pixel elements,driver circuits, etc. Housing 12 may include internal structures such asmetal frame members, a planar housing member (sometimes referred to as amidplate) that spans the walls of housing 12 (i.e., a substantiallyrectangular member that is welded or otherwise connected between theopposing right and left sides of member 16), printed circuit boards, andother internal conductive structures. These conductive structures may belocated in center CN of housing 12 (as an example).

In regions 22 and 20, openings may be formed between the conductivehousing structures and conductive electrical components that make updevice 10. These openings may be filled with air, plastic, or otherdielectrics. Conductive housing structures and other conductivestructures in region CN of device 10 may serve as a ground plane for theantennas in device 10. The openings in regions 20 and 22 may serve asslots in open or closed slot antennas, may serve as a central dielectricregion that is surrounded by a conductive path of materials in a loopantenna, may serve as a space that separates an antenna resonatingelement such as a strip antenna resonating element or an inverted-Fantenna resonating element from the ground plane, or may otherwise serveas part of antenna structures formed in regions 20 and 22.

Portions of member 16 may be provided with gap structures. For example,member 16 may be provided with one or more gaps such as gaps 18A, 18B,18C, and 18D, as shown in FIG. 1. The gaps may be filled with dielectricsuch as polymer, ceramic, glass, etc. Gaps 18A, 18B, 18C, and 18D maydivide member 16 into one or more peripheral conductive member segments.There may be, for example, two segments of member 16 (e.g., in anarrangement with two gaps), three segments of member 16 (e.g., in anarrangement with three gaps), four segments of member 16 (e.g., in anarrangement with four gaps, etc.). The segments of peripheral conductivemember 16 that are formed in this way may form parts of antennas indevice 10.

In a typical scenario, device 10 may have upper and lower antennas (asan example). An upper antenna may, for example, be formed at the upperend of device 10 in region 22. A lower antenna may, for example, beformed at the lower end of device 10 in region 20. The antennas may beused separately to cover separate communications bands of interest ormay be used together to implement an antenna diversity scheme or amultiple-input-multiple-output (MIMO) antenna scheme.

Antennas in device 10 may be used to support any communications bands ofinterest. For example, device 10 may include antenna structures forsupporting local area network communications, voice and data cellulartelephone communications, global positioning system (GPS) communicationsor other satellite navigation system communications, Bluetooth®communications, etc.

A schematic diagram of electronic device 10 is shown in FIG. 2. As shownin FIG. 2, electronic device 10 may include storage and processingcircuitry 28. Storage and processing circuitry 28 may include storagesuch as hard disk drive storage, nonvolatile memory (e.g., flash memoryor other electrically-programmable-read-only memory configured to form asolid state drive), volatile memory (e.g., static or dynamicrandom-access-memory), etc. Processing circuitry in storage andprocessing circuitry 28 may be used to control the operation of device10. This processing circuitry may be based on one or moremicroprocessors, microcontrollers, digital signal processors, basebandprocessors, power management units, audio codec chips, applicationspecific integrated circuits, etc.

Storage and processing circuitry 28 may be used to run software ondevice 10, such as internet browsing applications,voice-over-internet-protocol (VOIP) telephone call applications, emailapplications, media playback applications, operating system functions,etc. To support interactions with external equipment, storage andprocessing circuitry 28 may be used in implementing communicationsprotocols. Communications protocols that may be implemented usingstorage and processing circuitry 28 include internet protocols, wirelesslocal area network protocols (e.g., IEEE 802.11 protocols—sometimesreferred to as WiFi®), protocols for other short-range wirelesscommunications links such as the Bluetooth® protocol, cellular telephoneprotocols, etc.

Circuitry 28 may be configured to implement control algorithms thatcontrol the use of antennas in device 10. For example, to supportantenna diversity schemes and MIMO schemes or other multi-antennaschemes, circuitry 28 may perform signal quality monitoring operations,sensor monitoring operations, and other data gathering operations andmay, in response to the gathered data, control which antenna structureswithin device 10 are being used to receive and process data. As anexample, circuitry 28 may control which of two or more antennas is beingused to receive incoming radio-frequency signals, may control which oftwo or more antennas is being used to transmit radio-frequency signals,may control the process of routing data streams over two or moreantennas in device 10 in parallel, etc. In performing these controloperations, circuitry 28 may open and close switches, may turn on andoff receivers and transmitters, may adjust impedance matching circuits,may configure switches in front-end-module (FEM) radio-frequencycircuits that are interposed between radio-frequency transceivercircuitry and antenna structures (e.g., filtering and switching circuitsused for impedance matching and signal routing), and may otherwisecontrol and adjust the components of device 10.

Input-output circuitry 30 may be used to allow data to be supplied todevice 10 and to allow data to be provided from device 10 to externaldevices. Input-output circuitry 30 may include input-output devices 32.Input-output devices 32 may include touch screens, buttons, joysticks,click wheels, scrolling wheels, touch pads, key pads, keyboards,microphones, speakers, tone generators, vibrators, cameras, sensors,light-emitting diodes and other status indicators, data ports, etc. Auser can control the operation of device 10 by supplying commandsthrough input-output devices 32 and may receive status information andother output from device 10 using the output resources of input-outputdevices 32.

Wireless communications circuitry 34 may include radio-frequency (RF)transceiver circuitry formed from one or more integrated circuits, poweramplifier circuitry, low-noise input amplifiers, passive RF components,one or more antennas, and other circuitry for handling RF wirelesssignals. Wireless signals can also be sent using light (e.g., usinginfrared communications).

Wireless communications circuitry 34 may include satellite navigationsystem receiver circuitry such as Global Positioning System (GPS)receiver circuitry 35 (e.g., for receiving satellite positioning signalsat 1575 MHz). Transceiver circuitry 36 may handle 2.4 GHz and 5 GHzbands for WiFi® (IEEE 802.11) communications and may handle the 2.4 GHzBluetooth® communications band. Circuitry 34 may use cellular telephonetransceiver circuitry 38 for handling wireless communications incellular telephone bands such as bands at 850 MHz, 900 MHz, 1800 MHz,1900 MHz, and 2100 MHz or other cellular telephone bands of interest.Wireless communications circuitry 34 can include circuitry for othershort-range and long-range wireless links if desired. For example,wireless communications circuitry 34 may include global positioningsystem (GPS) receiver equipment, wireless circuitry for receiving radioand television signals, paging circuits, etc. In WiFi® and Bluetooth®links and other short-range wireless links, wireless signals aretypically used to convey data over tens or hundreds of feet. In cellulartelephone links and other long-range links, wireless signals aretypically used to convey data over thousands of feet or miles.

Wireless communications circuitry 34 may include antennas 40. Antennas40 may be formed using any suitable antenna types. For example, antennas40 may include antennas with resonating elements that are formed fromloop antenna structure, patch antenna structures, inverted-F antennastructures, closed and open slot antenna structures, planar inverted-Fantenna structures, helical antenna structures, strip antennas,monopoles, dipoles, hybrids of these designs, etc. Different types ofantennas may be used for different bands and combinations of bands. Forexample, one type of antenna may be used in forming a local wirelesslink antenna and another type of antenna may be used in forming a remotewireless link antenna.

A cross-sectional side view of device 10 of FIG. 1 taken along line24-24 in FIG. 1 and viewed in direction 26 is shown in FIG. 3. As shownin FIG. 3, display 14 may be mounted to the front surface of device 10.Housing 12 may include sidewalls formed from member 16 and one or morerear walls formed from structures such as planar rear housing structure42. Structure 42 may be formed from a dielectric such as glass, ceramic,or plastic, and/or metals or other suitable materials (e.g., fibercomposites). Snaps, clips, screws, adhesive, and other structures may beused in assembling the parts of housing 12 together.

Device 10 may contain printed circuit boards such as printed circuitboard 46. Printed circuit board 46 and the other printed circuit boardsin device 10 may be formed from rigid printed circuit board material(e.g., fiberglass-filled epoxy) or flexible sheets of material such aspolymers. Flexible printed circuit boards (“flex circuits”) may, forexample, be formed from flexible sheets of polyimide.

Printed circuit board 46 (which may, if desired, be mounted on aninternal housing member such as a metal plate) may contain interconnectssuch as interconnects 48. Interconnects 48 may be formed from conductivetraces (e.g., traces of gold-plated copper or other metals). Connectorssuch as connector 50 may be connected to interconnects 48 using solderor conductive adhesive (as examples). Integrated circuits, discretecomponents such as resistors, capacitors, and inductors, and otherelectronic components may be mounted to printed circuit board 46.

Antennas in device 10 such as illustrative antenna 40 of FIG. 3 may haveantenna feed terminals. For example, each antenna in device 10 may havea positive antenna feed terminal such as positive antenna feed terminal58 and a ground antenna feed terminal such as ground antenna feedterminal 54. As shown in the illustrative arrangement of FIG. 3, atransmission line path such as coaxial cable 52 may be coupled betweenthe antenna feed formed from terminals 58 and 54 and transceivercircuitry in components 44 via connector 50 and interconnects 48.Components 44 may include one or more integrated circuits forimplementing wireless circuitry 34 of FIG. 2 (e.g., receiver 35 andtransceiver circuits 36 and 38).

Connectors such as connector 50 may be used in coupling transmissionlines in device 10 to printed circuit boards such as board 46. Connector50 may be, for example, a coaxial cable connector that is connected toprinted circuit board 46 using solder (as an example). Cable 52 may be acoaxial cable or other transmission line. Examples of transmission linesthat may be used in device 10 include coaxial cables, microstrip andstripline transmission lines formed from a flex circuit or rigid printedcircuit board, transmission lines that are formed from multipletransmission line structures such as these, etc.

When coupled to the feed of antenna 40, transmission line 52 may be usedto transmit and receive radio-frequency signals using antenna 40. Asshown in FIG. 3, terminal 58 may be coupled to coaxial cable centerconnector 56. Terminal 54 may be connected to a ground conductor incable 52 (e.g., a conductive outer braid conductor). Other arrangementsmay be used for coupling transceivers in device 10 to antenna 40 ifdesired. For example, impedance matching circuits may be used incoupling transceiver circuitry to antenna structures. The arrangement ofFIG. 3 is merely illustrative.

In the illustrative example of FIG. 3, device 10 includes antenna 40. Toenhance signal quality and to cover multiple bands of interest, device10 may contain multiple antennas. With one suitable arrangement, whichis sometimes described herein as an example, a WiFi® antenna may belocated in region 22, a first (e.g., a primary) cellular telephoneantenna may be located in region 20, and a second (e.g., secondary)cellular telephone antenna may be located in region 22. The secondcellular telephone antenna may, if desired, be configured to receive GPSsignals.

The wireless circuitry of device 10 may be used to implement an antennadiversity scheme. The diversity scheme may support receiver diversityand/or transmitter diversity. For example, the wireless circuitry mayinclude multiple receivers each of which is associated with a respectiveantenna or may contain a multiplexer that can be used to route signalsfrom each of the antennas to a shared receiver (e.g., using a timemultiplexing arrangement). Receiver diversity may be implemented toallow the receiver that is receiving the best antenna signal to be used.Switching circuitry may be included to allow the antennas to be swappedin real time. For example, if it is determined that a particular antennais blocked during signal transmission operations, the switchingcircuitry can be used to connect the active transmitter circuit in thedevice to the antenna that is not blocked.

FIG. 4 is a circuit diagram of illustrative wireless circuitry 34 thatmay include resources for implementing receiver diversity andtransmitter diversity in an electronic device with two cellulartelephone antennas. In the example of FIG. 4, wireless circuitry 34includes cellular telephone antenna 40L, cellular telephone antenna 40U,and wireless local area network antenna 40WF. Cellular telephone antenna40L may be a lower cellular telephone antenna that is located at lowerend 20 of device 10. Cellular telephone antenna 40U may be an uppercellular telephone antenna that is located at upper end 22 of device 10.If desired, additional antennas may be provided that support cellulartelephone network communications. The illustrative arrangement of FIG. 4in which there are two cellular antennas in wireless circuitry 34 ismerely illustrative.

As shown in FIG. 4, wireless circuitry 34 may have input-output portssuch as ports 100 and 130 for interfacing with digital data circuits instorage and processing circuitry 28. Wireless circuitry 34 may includeone or more integrated circuits for implementing transceiver circuitssuch as baseband processor 102 and cellular telephone transceivercircuitry 38. Cellular telephone transceiver circuitry 38 may have atransmit-receive port (TX/RX port) and a receive port (RX port).

Port 100 may receive digital data from storage and processing circuitry28 that is to be transmitted by transmitter 104 in transceiver circuitry38. Incoming data that has been received by transceiver circuitry 38 andbaseband processor 102 may be supplied to storage and processingcircuitry 28 via port 100.

Port 130 may be used to handle digital data associated with transmittedand received wireless local area network signals such as WiFi® signals(as an example). Outgoing digital data that is supplied to port 130 bystorage and processing circuitry 28 may be transmitted using wirelesslocal area network transceiver circuitry 36, paths such as path 128, andone or more antennas such as antenna 40WF. During data receptionoperations, signals received by antenna 40WF may be provided totransceiver 36 via path 128. Transceiver 36 may convert the incomingsignals to digital data. The digital data may be provided to storage andprocessing circuitry 28 via port 130. If desired, local signals such asBluetooth® signals may also be transmitted and received via antennassuch as antenna 40WF.

Transceiver circuitry 38 may include one or more transmitters and one ormore receivers. Transceiver circuitry 38 may be coupled to antennas 40Uand 40L using switching circuitry such as switch 126. The configurationof switch 126 may be controlled by control signal P1-P2 _(—)SELECT onpath 117. Control circuitry in device 10 such as baseband processor 120may control the state of signal P1-P2_SELECT to optimize antennaperformance in real time.

As shown in FIG. 4, switch 126 may have four ports (terminals): T1, T2,T3, and T4. Switch 126 may have a first position (P1) and a secondposition (P2).

When P1-P2_SELECT has a first value, switch 126 will be placed inposition P1. In this mode of operation, port T1 will be connected toport T2 and port T3 will be connected to port T4. When ports T1 and T2are connected, outgoing signals from transceiver circuitry 38 will bepassed to antenna 40L and incoming signals from antenna 40L will bepassed to transceiver circuitry 38. When ports T3 and T4 are connected,incoming signals from antenna 40U will be passed to transceivercircuitry 38.

When P1-P2_SELECT has a second value, switch 126 will be placed inposition P2. In this mode of operation, port T1 will be connected toport T4 and port T3 will be connected to port T2. When ports T1 and T4are connected, outgoing signals from transceiver circuitry 38 will bepassed to antenna 40U and incoming signals from antenna 40U will bepassed to transceiver circuitry 38. When ports T3 and T2 are connected,incoming signals from antenna 40L will be passed to transceivercircuitry 38.

Transmitter 104 and receivers 110 (i.e., receiver RX1 and receiver RX2)may be used to handle cellular telephone communications. Signals thatare received by transmitter 104 over path 118 may be supplied to poweramplifier 106 by transmitter 104. Power amplifier 106 may strengthenthese outgoing signals for transmission through port T1 (and thereafterover antenna 40L or antenna 40U, depending on the state of switch 126).Incoming signals that are provided to port T1 (i.e., from antenna 40L orantenna 40U depending on the state of switch 126) may be amplified usinglow noise amplifier 112. Signals received by low noise amplifier 112 maybe provided to receiver RX1. Receiver RX1 may provide received data toprocessor 102 via path 118. Incoming signals that are provided to portT3 (i.e., from antenna 40L or antenna 40U depending on the state ofswitch 126) may be amplified using low noise amplifier 124. Signalsreceived by low noise amplifier 124 may be provided to receiver RX2.Receiver RX2 may provide received data to processor 102 via path 118.Circuits such as transmitter 104 and receivers 110 may each havemultiple ports (e.g., for handling different respective communicationsbands) and may be implemented using one or more individual integratedcircuits.

Antennas 40U and 40L may be coupled to transceiver circuitry 38 usingcircuitry such as impedance matching circuitry, filters, and switches(e.g., switch 126). This circuitry, which is sometimes referred to asfront-end module (FEM) circuitry, can be controlled by storage andprocessing circuitry in device 10 (e.g., control signals from aprocessor such as baseband processor 102). As shown in the example ofFIG. 4, the front-end circuitry in wireless circuitry 34 may includeimpedance matching circuitry 108 such as matching circuit M1 andmatching circuit M2. Impedance matching circuitry 108 may be formedusing conductive structures with associated capacitance, resistance, andinductance values, and/or discrete components such as inductors,capacitors, and resistors that form circuits to match the impedances oftransceiver circuitry 38 and antennas 40U and 40L. Matching circuit M1may be coupled between wireless transceiver circuitry 38 (includingassociated its amplifier circuitry and switching circuitry 126) andantenna 40L. Matching circuit M2 may be coupled between transceivercircuitry 38 (and its associated amplifier circuitry and switchingcircuitry 126) and antenna 40U. Paths such as paths 120 and 122 may beused to couple matching circuitry 108 to antennas 40L and 40U.

Matching circuits M1 and M2 may be fixed or adjustable. For example,matching circuit M1 may be fixed and matching circuit M2 may beadjustable. In this type of configuration, a control circuit such asbaseband processor 102 may issue control signals such as signal SELECTon path 116 during operation of wireless circuitry 34. Signal SELECT maybe distributed to matching circuit M2. When SELECT has a first value,matching circuit M2 may be placed in a first configuration. When SELECThas a second value, matching circuit M2 may be placed in a secondconfiguration. The state of matching circuit M2 may serve to tuneantenna 40U so that different communications bands are covered byantenna 40U.

Illustrative tunable circuitry that may be used for implementingmatching circuit M2 of FIG. 4 is shown in FIG. 5. As shown in FIG. 5,matching circuit M2 may have switches such as switches 134 and 136.Switches 134 and 136 may have multiple positions (shown by theillustrative A and B positions in FIG. 5). When signal SELECT has afirst value, switches 134 and 136 may be put in their A positions andmatching circuit MA may be switched into use. When signal SELECT has asecond value, switches 134 and 136 may be placed in their B positions(as shown in FIG. 5), so that matching circuit MB is connected betweenpaths 132 and 122.

By adjusting matching circuit M2, the frequency response of antenna 40Umay be tuned as needed. For example, antenna 40U may be placed in oneconfiguration when it is desired to cover a set of communications bandsthat are commonly used in a one country and may be placed in anotherconfiguration when it is desired to cover a set of communications bandsthat are commonly used in another country.

In wireless circuitry with tunable matching circuitry such as circuitry34 of FIG. 4, antenna 40U may be able to cover a wider range ofcommunications frequencies than would otherwise be possible. The use oftuning for antenna 40U may therefore allow a relatively narrow bandwidth(and potentially compact) design to be used for antenna 40U, if desired.

As shown in FIG. 4, control signals such as RX_CONTROL may be providedto receiver circuitry 110 using a path such as path 119. Using thesecontrol signals, wireless circuitry 34 can selectively activatereceivers RX1 and RX2 or can otherwise select which incoming antennasignals are being received.

The operation of device 10 may involve real time control of switchingcircuitry such as switching circuitry 126, transceiver circuitry 38(e.g., receiver circuitry 110), and matching circuitry such as matchingcircuitry 108. Antennas 40U and 40L may be implemented using structuresthat cover the same sets of communications bands or that cover differentbut overlapping sets of communications bands.

Antenna 40L may be located at the lower end of device housing 12,whereas antenna 40U may be located at the upper end of device housing12. In this type of configuration, antenna 40L will tend to be locatedfarther from the head of a user during operation of device 10 (e.g.,when device 10 is a handheld device such as a cellular telephone and isused in the orientation shown in FIG. 1). Because of its location, itmay be possible to increase transmitter power levels more when usingantenna 40L to transmit radio-frequency signals than when using antenna40U to transmit radio-frequency signals, while satisfying regulatorylimits on emitted radiation such as specific absorption rate (SAR)limits. Antenna 40L may also cover more bands and/or may be moreefficient in certain bands than antenna 40U. Because of considerationssuch as these, antenna 40L may sometimes be referred to as being theprimary antenna for device 10 and antenna 40U may sometimes be referredto as being the secondary antenna for device 10.

Transceiver port TX/RX may sometimes be referred to as forming atransmit-receive port, because port TX/RX (and associated switch portT1) handles transmitted signals from transmitter 104 and receivedsignals associated with receiver RX1. Transceiver port RX may sometimesbe referred to as forming a receive port (receive-only port), becauseport RX (and associated switch port T3) are used in providing receivedsignals to receiver RX2.

During operation, processing circuitry in device 10 such as basebandprocessor 102 can adjust signals P1-P2_SELECT, RX_CONTROL, and SELECT orother suitable control signals in real time so that overall antennaperformance is optimized, even as the performance of each individualantenna varies due to environmental factors. Examples of factors thatmay influence antenna performance include the position of device 10relative to the user's body and the surrounding environment, theorientation of each antenna relative to its surroundings, and otherfactors that influence signal losses in the respective paths betweeneach antenna and the remote cellular telephone base station equipmentwith which device 10 is communicating.

To determine how wireless circuitry 34 should be configured, processingcircuitry such as baseband processor 102 may monitor signal quality foreach antenna. For example, processor 102 may determine received signalquality as reflected by received signal metrics such a bit error rate,frame error rate, signal to noise ratio, other noise values, fraction ofdropped packets, received signal strength, etc. Transmitted signalquality for an antenna may be inferred from received signal qualityusing the same antenna or may be determined based on information oncell-tower-specified transmit powers, information on transmitted signalquality that is received from an associate base station, etc. Signalquality information may be gathered for antennas 40L and 40U byperiodically switching between antennas 40L and 40U (e.g., when sharinga receiver) or by using receiver RX1 to measure signals from one antennawhile using receiver RX2 to measure signals from the other antenna.

Sensor data may also be monitored. For example, device 10 may beprovided with proximity sensors or other circuitry that is able toascertain whether each antenna is being blocked (e.g., by an externalobject such as a part of a user's body, etc.). Data from one or moreproximity sensors may be monitored by processor 102 to determine whethercorresponding antennas that are located adjacent to the proximitysensors are being adversely affected by the presence of the externalobject.

Whenever data from a sensor, data from a cellular network, and/or datathat device 10 has gathered on received signal quality or other dataindicates that the performance of a particular antenna is notacceptable, processor 102 can adjust wireless circuitry 34 in real timeto optimize antenna performance.

Consider, as an example, a situation in which it is determined thatantenna 40L is performing better than antenna 40U (e.g., because antenna40U is partially blocked by an external object and/or because antenna40L is more efficient than antenna 40U). In this situation, switch 126may be placed in position P1. In this configuration, the TX/RX port andport T1 of switch 126 will be coupled to antenna 40L, so antenna 40L maybe used for transmit and receive operations associated with the TX/RXport and port T1. Receiver RX2 may monitor signal quality for antenna40U using the RX port of transceiver circuitry 38.

If received signals from antenna 40L drop in quality relative toreceived signals from antenna 40U or if other suitable criteria aresatisfied, the antenna assignments in wireless circuitry 34 can beswapped by placing switch 126 in position P2. In this configuration, theTX/RX port of transceiver circuitry 38 will be coupled to antenna 40Uand signals from the TX/RX port can be transmitted and received throughantenna 40U. The receive port of transceiver circuitry 38 can be used tomonitor signal quality for antenna 40L. If signal quality with antenna40U remains high (as indicated by received signal monitoring datagathered from antennas 40U and 40L using receivers RX1 and RX2, sensordata, or other information), switch 126 can be maintained in positionP2. If, however, processor 102 determines that signal quality would bebetter if signals were handled by antenna 40L, switch 126 can bereturned to position P1.

If desired (e.g., when implementing MIMO schemes), multiple receiverports may be simultaneously used to handle independent streams of dataeach of which is associated with a respective antenna.

FIG. 6 is a top view of the interior of device 10 showing how antennas40L, 40U, and 40WF may be implemented within housing 12. As shown inFIG. 6, ground plane G may be formed within housing 12. Ground plane Gmay form antenna ground for antennas 40L, 40U, and 40WF. Because groundplane G may serve as antenna ground, ground plane G may sometimes bereferred to as antenna ground, ground, or a ground plane element (asexamples).

In central portion C of device 10, ground plane G may be formed byconductive structures such as a conductive housing midplate member thatis connected between the left and right edges of member 16, printedcircuit boards with conductive ground traces, etc. At ends 22 and 20 ofdevice 10, the shape of ground plane G may be determined by the shapesand locations of conductive structures that are tied to ground. Examplesof conductive structures that may overlap to form ground plane G includehousing structures (e.g., a conductive housing midplate structure, whichmay have protruding portions), conductive components (e.g., switches,cameras, data connectors, printed circuits such as flex circuits andrigid printed circuit boards, radio-frequency shielding cans, buttonssuch as button 144 and conductive button mounting structure 146, etc.),and other conductive structures in device 10. In the illustrative layoutof FIG. 6, the portions of device 10 that are conductive and tied toground to form part of ground plane G are shaded and are contiguous withcentral portion C.

Openings such as openings 138 and 146 may be formed between ground planeG and respective portions of peripheral conductive member 16. Openings138 and 146 may be filled with air, plastic, and other dielectrics.Openings 138 and 146 may be associated with antenna structures 40.

Lower antenna 40L may be formed by a loop antenna structure having ashape that is determined at least partly by the shape of the lowerportions of ground plane G and conductive housing member 16. In theexample of FIG. 6, opening 138 is depicted as being rectangular, butthis is merely illustrative. In practice, the shape of opening 138 maybe dictated by the placement of conductive structures in region 20 suchas a microphone, flex circuit traces, a data port connector, buttons, aspeaker, etc.

Lower antenna 40L may be fed using an antenna feed made up of positiveantenna feed terminal 58-1 and ground antenna feed terminal 54-1.Transmission line 52-1 (see, e.g., path 122 of FIG. 4) may be coupled tothe antenna feed for lower antenna 40L. Gap 18B may form a capacitancethat helps configure the frequency response of antenna 40L. If desired,device 10 may have conductive housing portions, matching circuitelements, and other structures and components that help match theimpedance of transmission line 52-1 to antenna 40L (see, e.g.,illustrative matching circuit M1 of FIG. 4).

Antenna 40WF may have an antenna resonating element formed from a stripof conductor such as strip 142. Strip 142 may be formed from a trace ona flex circuit, from a trace on a rigid printed circuit board, from astrip of metal foil, or from other conductive structures. Antenna 40WFmay be fed by transmission line 52-2 (see, e.g., path 128 of FIG. 4)using antenna feed terminals 58-2 and 54-2.

Antenna 40U may be a two-branch inverted-F antenna. Transmission line52-3 (see, e.g., path 120 of FIG. 4) may be used to feed antenna 40U atantenna feed terminals 58-3 and 54-3. Conductive structure 150 may bebridge dielectric opening 140 and may be used to electrically shortground plane G to peripheral housing member 16. Conductive structure 148and matching circuit M2 may be used to connect antenna feed terminal58-3 to peripheral conductive member 16 at point 152. Conductivestructures such as structures 148 and 150 may be formed by flex circuittraces, conductive housing structures, springs, screws, or otherconductive structures.

Gaps such as gaps 18B, 18C, and 18D may be present in peripheralconductive member 16. (Gap 18A of FIG. 1 may be absent or may beimplemented using a phantom gap structure that cosmetically looks like agap from the exterior of device 10, but that is electrically shortedwithin the interior of housing 12 so that no gap is electrically presentin the location of gap 18A.) The presence of gaps 18B, 18C, and 18D maydivide peripheral conductive member 16 into segments. As shown in FIG.6, peripheral conductive member 16 may include first segment 16-1,second segment 16-2, and third segment 16-3.

Segment 16-1 may form antenna resonating element arms for antenna 40U.In particular, a first portion (segment) of segment 16-1 (having armlength LBA) may extend from point 152 (where segment 16-1 is fed) to theend of segment 16-1 that is defined by gap 18C and a second portion(segment) of segment 16-1 (having arm length HBA) may extend from point152 to the opposing end of segment 16-1 that is defined by gap 18D. Thefirst and second portions of segment 16-1 may form respective branchesof an inverted F antenna and may be associated with respective low band(LB) and high band (HB) antenna resonances for antenna 40U.

Antenna 40L may, as an example, cover the transmit and receive sub-bandsin five communications bands (e.g., 850 MHz, 900 MHz, 1800 MHz, 1900MHz, and 2100 MHz). Antenna 40U may be configured to cover these samefive communications bands or may be configured to cover a subset of thebands covered by antenna 40L.

A table showing illustrative bands that may be covered by antennas 40U(e.g., the upper antenna in device 10 at upper end 22 of housing 12) and40L (e.g., the lower antenna in device 10 at lower end 20 of housing 12)as a function of the state of matching circuit M2 (i.e., state MA or MB)and as a function of the position of switch 126 are shown in FIG. 7.

The rightmost column of the table of FIG. 7 indicates the position ofswitch 126 (P1 or P2) and the leftmost column of the table of FIG. 7indicates the resulting transmit and receive mode for wireless circuitry34. Each row in the column contains entries that specify how well theantenna listed in the second-to-leftmost column handles variouscommunications bands. Entries marked with “H” indicate that a band iscovered. Entries marked with an “L” indicate that a band is covered lessefficiently than for an “H” entry. Entries marked with an “M” indicatethat a band is covered with more efficiency than an “L” entry, but withless efficiency than for an “H” entry. Blank cells correspond to bandsthat are not covered. The circled entries indicate which of the coveredbands are used for each antenna when operated using wireless circuitry34 of FIG. 4.

When switch 126 is in position P1, the TX/RX port of transceivercircuitry 38 (i.e., the port of circuitry 38 that is coupled to switchport T1) will be coupled to lower antenna 40L and upper antenna 40U willfunction as a “receive-only” antenna that feeds signals to receiver RX2(e.g., for signal quality monitoring), as indicated by the top threerows of the FIG. 7 table. The state of matching circuit M2 (ascontrolled by signal SELECT) will determine whether upper antenna 40Ufunctions in mode MA (the first row of the table) or mode MB (the secondrow of the table). As shown in the table, in the MA mode, the upperantenna can be used to receive signals in the 850 RX band (the 850 MHzreceive band) and 1900 RX band (the 1900 receive band). In the MB mode,the upper antenna can be used to receive signals in the 900 RX band, the1800 RX band, and the 2100 RX band. The lower antenna can be used totransmit and receive in all five listed cellular telephonecommunications bands (850 MHz, 900 MHz, 1800 MHz, 1900 MHz, and 2100MHz).

When switch 126 is in position P2, the TX/RX port of transceivercircuitry 38 will be coupled to upper antenna 40U and lower antenna 40Lwill function as a “receive-only” antenna that feeds signals to receiverRX2 (e.g., for signal quality monitoring), as indicated by the bottomthree rows of the FIG. 7 table. The state of matching circuit M2 willdetermine whether upper antenna 40U functions in mode MA (the fourth rowof the table) or mode MB (the fifth row of the table). As shown in thetable, in the MA mode, the upper antenna can be used to transmit signalsin the 850 TX and 1900 TX bands and can receive signals in the 850 RXand 1900 RX bands. In the MB mode, the upper antenna can be used totransmit signals in the 900 TX, 1800 TX, and 2100 TX bands and canreceive signals in the 900 RX band, the 1800 RX band, and the 2100 RXband. When switch 126 is in position P2, the lower antenna can be usedto receive signals (e.g., to monitor signal quality) in all five listedcellular telephone communications bands (850 MHz, 900 MHz, 1800 MHz,1900 MHz, and 2100 MHz).

Antenna structures with different band coverage than the coverage listedin the FIG. 7 table may be used in device 10 if desired. The antennaresponses of the FIG. 7 table are merely illustrative.

Illustrative steps involved in operating device 10 using wirelesscircuitry such as wireless circuitry 34 of FIG. 4 are shown in FIG. 8.As step 200, device 10 may gather information on the performance ofantenna 40L and antenna 40U. For example, signal quality metrics such asbit error rate, frame error rate, signal strength, noise, or otherindicators of received quality may be measured and information on thequality of transmitted signals may be gathered (e.g., using feedbackfrom a cellular network). Data from proximity sensors may also beevaluated to determine whether antenna performance is being affected (oris likely being affected). The data that is gathered during theoperations of step 200 may be evaluated (e.g., using storage andprocessing circuitry 28 such as baseband processor 102) to determine howto optimally adjust wireless circuitry 34.

During the operations of step 202, in response to the information on theperformance of antennas 40L and 40U that was obtained during step 200,wireless circuitry 34 may be configured in real time. For example, if itis determined that an adjustment to switch 126 will result in improvedantenna performance for transmitting signals, switch 126 may be adjustedaccordingly. Matching circuit adjustments to matching circuit M2 may bemade to ensure that upper antenna 40U covers desired bands of interest(e.g., depending on the country in which device 10 is located).

During the operations of step 204, the optimal settings that wereselected at step 202 may be used to operate wireless circuitry 34 anddevice 10. Periodically, or in response to satisfaction of predeterminedcriteria, control may loop back to step 200 as indicated by line 206.Upon returning to step 200, updated antenna performance data may beobtained and evaluated to determine whether further adjustments to theconfiguration of wireless circuitry 34 should be made.

The foregoing is merely illustrative of the principles of this inventionand various modifications can be made by those skilled in the artwithout departing from the scope and spirit of the invention.

What is claimed is:
 1. An electronic device, comprising: a housinghaving peripheral conductive housing structures that run around at leastfirst, second, third, and fourth edges of the housing, wherein the firstedge opposes the third edge and the second edge opposes the fourth edge;an antenna ground, wherein the antenna ground is formed at least partlyfrom conductive portions of the housing; a first dielectric-filled gapin the peripheral conductive housing structures along the first edge ofthe housing; a second dielectric-filled gap in the peripheral conductivehousing structure along the third edge of the housing; and an inverted-Fantenna that includes an antenna resonating element arm formed from asegment of the peripheral conductive housing structures that extendsfrom the first dielectric-filled gap to the second dielectric-filledgap, the antenna ground, a conductive structure coupled between theantenna resonating element arm and the antenna ground, and an antennafeed having a positive feed terminal coupled to the segment of theperipheral conductive housing structures and a ground feed terminalcoupled to the antenna ground.
 2. The electronic device defined in claim1, further comprising: a third dielectric-filled gap in the peripheralconductive housing structures along the first edge of the housing; and afourth dielectric-filled gap in the peripheral conductive housingstructures along the third edge of the housing.
 3. The electronic devicedefined in claim 2, wherein a first additional segment of the peripheralconductive housing structures extending between the first and thirddielectric-filled gaps and a second additional segment of the peripheralconductive housing structures extending between the second and fourthdielectric-filled gaps form part of the antenna ground.
 4. Theelectronic device defined in claim 1, wherein the electronic device hasa length, a width that is less than the length, and a height that isless than the width, and the peripheral conductive housing structuresand the first and second dielectric-filled gaps each extend across theheight of the electronic device.
 5. The electronic device defined inclaim 4, further comprising: a display that forms a front face of theelectronic device and extends across the length and the width of theelectronic device.
 6. The electronic device defined in claim 5, whereinthe housing comprises a rear housing wall that forms a rear face of theelectronic device.
 7. The electronic device defined in claim 6, whereinthe rear housing wall comprises a conductive rear housing wall.
 8. Theelectronic device defined in claim 6, wherein the rear housing wallcomprises glass and metal.
 9. The electronic device defined in claim 5,further comprising: a planar conductive layer that forms a portion ofthe antenna ground, that extends from the first edge to the third edgeof the housing, and that is separated from the segment of the peripheralconductive housing structures by a slot, wherein the antenna feed iscoupled across the slot.
 10. The electronic device defined in claim 9,further comprising: a glass structure that forms a rear face of theelectronic device and extends between the peripheral conductive housingstructures.
 11. The electronic device defined in claim 1, wherein thesegment of the peripheral conductive structures comprises a firstportion that runs along the first edge of the housing and that definesan edge of the first dielectric-filled gap, a second portion that runsalong the second edge of the housing, and a third portion that runsalong the third edge of the housing and defines an edge of the seconddielectric-filled gap.
 12. An electronic device having a rectangularperiphery, comprising: a housing having peripheral conductive structuresthat run around the rectangular periphery of the electronic device; afirst dielectric-filled gap in the peripheral conductive structures thatseparates a first segment of the peripheral conductive structures from asecond segment of the peripheral conductive structures; a seconddielectric-filled gap in the peripheral conductive structures thatseparates the first segment of the peripheral conductive structures froma third segment of the peripheral conductive structures; an antennaground that includes a conductive layer that extends from the secondsegment of the peripheral conductive structures to the third segment ofthe peripheral conductive structures, wherein the first segment of theperipheral conductive structures is separated from the conductive layerby a slot; and an antenna feed coupled across the slot, wherein thefirst segment of the peripheral conductive structures has a firstportion that extends along a first side of the rectangular periphery, asecond portion that extends across a second side of the rectangularperiphery, and a third portion that extends along a third side of therectangular periphery.
 13. The electronic device defined in claim 12,wherein the second segment of the peripheral conductive structures runsalong the first side of the rectangular periphery.
 14. The electronicdevice defined in claim 13, wherein the third segment of the peripheralconductive structures runs along the third side of the rectangularperiphery.
 15. The electronic device defined in claim 14, wherein theelectronic device has a length, a width that is less than the length,and a height that is less than the width, the first segment of theperipheral conductive structures extends across the width, and thefirst, second, and third segments of the peripheral conductivestructures and the first and second dielectric-filled gaps each extendacross the height of the electronic device.
 16. The electronic devicedefined in claim 15, wherein the first segment of the peripheralconductive structures forms an antenna resonating element arm, theelectronic device further comprising: a conductive structure coupledbetween the antenna resonating element arm and the antenna ground acrossthe slot.
 17. An electronic device having a length, a width that is lessthan the length, and a height that is less than the width, theelectronic device comprising: first and second peripheral conductivehousing walls that extend across the length and the height of theelectronic device; third and fourth peripheral conductive housing wallsthat extend between the first and second peripheral conductive housingwalls and that extend across the width and the height of the electronicdevice; a display that forms a front face of the electronic device; ahousing wall that forms a rear face of the electronic device; first andsecond dielectric-filled gaps in the first peripheral conductive housingwall that extend across the height of the electronic device; and thirdand fourth dielectric-filled gaps in the second peripheral conductivehousing wall that extend across the height of the electronic device,wherein the first, second, and third peripheral conductive housing wallsform antenna structures for an antenna in the electronic device.
 18. Theelectronic device defined in claim 17, further comprising: a conductivelayer that forms at least part of an antenna ground for the antenna,wherein the housing wall that forms the rear face of the electronicdevice comprises a glass structure that extends between the first,second, third, and fourth peripheral conductive housing walls.
 19. Theelectronic device defined in claim 18, further comprising: a first slotthat separates the second peripheral conductive housing wall from theconductive layer; and a second slot that separates the fourth peripheralconductive housing wall from the conductive layer.
 20. The electronicdevice defined in claim 19, further comprising: an antenna feed having afirst feed terminal coupled to the third peripheral conductive housingwall and a second feed terminal coupled to the conductive layer.